In U.S. Pat. No. 3,121,319 (the inventor being the same as in the present invention), there is shown a lockable latching assembly, where there is a latch bolt which is urged outwardly by a compression spring, with the latch bolt being retracted by operation of a slide bar which is in turn connected to oppositely positioned push buttons. The slide bar has two sets of cam faces positioned at approximately a 45.degree. angle to the lengthwise axis of the slide bar. When the slide bar is moved in either direction, one of these sets of cam faces acts on protrusions at the inner end of the latch bolt to retract the latch bolt. To lock the latch assembly, there is provided a locking rod that is mounted for a limited rotation within the slide bar. In one position, this locking rod permits the latch bolt to freely retract, with the locking rod fitting in a gap between two protruding members attached to legs of the latch bolt. On the other hand, when the locking rod is rotated 90.degree. to a locking position, the greater width dimension of the locking rod blocks the retracting movement of the latch bolt. On one side of the latching assembly, the locking rod is rotated by a lock barrel that is operated by a key. On the other side of the latching device, the locking rod is moved from its locked to its unlocked position simply by rotating the push button.
Usually, the side of the device that has the lock barrel is positioned at some exterior location (e.g., outside of the building, or on the outside of a room), while the other push button (which we will call the "inside" push button) is located within a room or within a structure. As indicated above, as disclosed in U.S. Pat. No. 3,121,319, to retract the latch from an inside location so that the door can be opened, it is necessary to first have the inside button positioned so that the locking rod is in the unlocked position.
Such locking devices have been manufactured commercially for a number of years and have operated quite satisfactorily. However, there is a requirement for improvement, and this relates to what may be called the "panic release" situation. If a person is operating the latching device from the inside, and if there is some emergency (e.g., smoke or a fire), the person may not have the presence of mind to make sure that the inside push button is in the unlocked position. To alleviate this situation, it is desirable that the person on the inside be able to unlatch the door simply by pushing the button, regardless of whether or not the push button is in the locked or unlocked position. Yet this must be accomplished in a manner to prevent a person on the "outside" from unlatching the latched assembly without a key.
Also in U.S. Pat. No. 3,121,319, there is a resilient spring device to yieldingly position the locking rod in its locked and unlocked position. This is accomplished by providing the locking rod with flat surface portions that engage spring members which yieldingly hold the locking rod in its two operating positions, while permitting 90.degree. rotation of the locking rod. The present invention is also intended to provide an improved locating spring assembly for the locking assembly.
The present invention is directed toward these problems, and the structure and function of the latching assembly of the present invention is in many respects quite similar to that of U.S. Pat. No. 3,121,319.
A search of the prior art has disclosed other latching devices of interest, and these will be discussed below.
U.S. Pat. No. 2,960,858 (the inventor being D. E. C. Webster, the inventor herein) discloses a latching device, the basic operation of which is rather similar to the above-mentioned U.S. Pat. No. 3,121,319.
U.S. Pat. No. 2,092,225--Schreiber shows a door latch system where there are slanted cam faces that force the bolt inwardly to the retracted position.
U.S. Pat. No. 2,058,163--Malone shows a door latching system where there are two slanted cam-like elements that operate to retract the bolt. The cam rod 31 is operated by the handle on the key side, and the dual cam members 31 are operated by the handle on the other side.